1. Field of the Invention
This invention is related to coaxial electrical connectors. More particularly, this invention is related to mating plug and jack coaxial electrical connectors that are used to connect two coaxial cables and include a means for locking the two connectors together so that the force required to disconnect the plug and jack coaxial connectors is greater than the force required to mate the two mating connectors. Furthermore, this invention is related to the use of plug and jack coaxial connectors that are located in molded outer housings. This invention is also related to the use of coaxial electrical connectors in automotive applications.
2. Description of the Prior Art
Coaxial or RF plug and jack electrical connectors typically include means for connecting center conductors in separate coaxial cables and for connecting the outer shield or braid in the two cables. In some cases, the center conductor in one of the cables is connected directly to a socket terminal in the other coaxial connector, but often a pin is attached or crimped to the center conductor in the cable. The center contact and the braid contact in each connector or terminal are typically separated by a cylindrical dielectric surrounding the center contact. The outer contact is typically attached to the braid or shield of a coaxial cable by crimping a ferrule to the braid after the end of the cable has been prepared or stripped.
Once plug and jack coaxial connectors have been attached to sections of a coaxial cable, a number of conventional means have been employed to mate the plug connector to the jack connector. One connector may employ an outer ring with internal threads which can then be screwed to the mating connector with external mating threads. BNC style coaxial connectors employ a laterally facing pin or post on one connector that is captured within a slot on the mating connector. However, both of these coaxial connector configurations require that mating connectors must be mounted by rotating one connector relative to its mating connector. This approach may be satisfactory for many traditional applications, such as field assembly of two coaxial cables, for example connecting two cables in a commercial or residential building. However, when the coaxial cables are used in a larger component or subassembly, such as a harness in an automobile or motor vehicle, that is assembled in a large scale production environment, screwing the two coaxial connectors together is undesirable. Indeed assembly workers have complained that assembly of components in this manner can cause problems with carpal tunnel syndrome.
One alternative to coaxial connectors that are mated by screwing one connector to another, is to employ a snap-on or quick connect, quick disconnect configuration in which one coaxial connector is simply pushed into mating engagement with the other coaxial connector without mutual rotation. These prior art snap-on connectors typically include a plurality of screw machined or die cast spring fingers in a cylindrical configuration. Adjacent spring fingers are separated by slots and include mating ridges adjacent their free ends. The individual spring fingers can be radially when pushed onto a mating connector having a diameter that differs from the normal neutral position of the spring fingers. The spring fingers can be deflected inwardly or outwardly, depending on whether they a inserted into a bore in cylindrical sleeve or over the exterior of a cylindrical barrel. When the quick connect, quick disconnect, snap-on connectors are fully mated, the spring fingers are received within a groove or recess on the mating connector, so that the spring fingers return to their neutral position. Examples of coaxial connectors of this general type are shown in U.S. Pat. Nos. 4,017,139; 4,412,717; 5,842,872; and 6,036,540. Although conventional coaxial connectors of this type do not require rotational movement for mating, the disconnect force is typically approximately the same as the connection or mating force. Thus quick connect, quick disconnect coaxial connectors cannot be locked when mated, so that a significantly greater force is required to unmate or disconnect the coaxial connectors than was required to mate them. The fact that these prior art connectors cannot be locked together can cause problems when they are used in automotive applications or in harness assemblies for use in similar applications, because the connectors can be inadvertently dislodged during assembly or pulled apart when a force is applied to one of the coaxial cables, possibly as part of a later assembly operation. Vibration due to movement of the automobile or similar apparatus can also cause disengagement of the mated coaxial connectors.
Prior art coaxial connectors, of either the rotationally mated or snap-on type are not typically positioned within molded or plastic housings. Exceptions include multiple position connectors in which multiple coaxial cables attached to separate cables are mounted in multi-position housing that is to be mated with printed circuit board connectors located in an array. U.S. Pat. Nos. 4,008,941 and 5,842,872 show multi-position configurations of this type. However, these patents show coaxial contacts that are inserted into cavities that extend completely through one piece housings. U.S. Pat. No. 5,547,400 shows a printed circuit board type coaxial connector that is mounted in a two piece housing.
One of the objects of the invention disclosed and claimed herein is to provide a mating coaxial cable assembly in which the force required to unmate the two connectors is substantially greater than the force required to mate the two connectors so that the connectors can be said to be in a locked configuration when mated. Of course, it should still be possible to unlock or unmate the two connectors when sufficient force is applied, but this unmating force or the manipulation of the connectors to disconnect them, should not occur during their normal use, and it should require more than the application of a tensile force to disengage the two connector assemblies.
Another objective of this invention is employ an assembly that uses a standard, tested, and reliable mating interface or configuration for the coaxial connectors or terminals used to connect two coaxial conductors, such as two cables or one cable to be connected to one printed circuit board. A standard cable termination technique should also be retained.
This invention should also be suitable for use in automotive applications and for use on cables that are part of harness assemblies that are used in motor vehicles and other similar applications. When installed as part of an automotive assembly operation, the coaxial connectors comprising this invention should be mated and unmated in substantially the same manner as other electrical connectors. It is also important that the mating force of connectors used in such applications not exceed the mating force typically required to mate other noncoaxial electrical connectors used as part of the same assembly, so that they can be reliably installed and do not require special care on the part of the installer.
These and other objectives can be achieved by the coaxial connector assembly disclosed herein that includes a plug coaxial assembly matable with a jack coaxial assembly. The plug coaxial assembly includes a plug coaxial connector and a molded plug housing, which is formed by two plug housing components latched together around the plug coaxial connector. The jack coaxial assembly includes a jack coaxial connector and a molded jack housing, which is formed of two jack housing components latched together around the jack coaxial connector. The plug coaxial connector is latched to the jack coaxial connector when mated, and the molded plug housing is separately latched to the molded jack housing when the plug coaxial assembly is mated to the jack coaxial assembly.
In this assembly, the plug housing includes a plug latch and the jack housing including a jack latch. The plug latch is matable with the jack latch with an engagement force. The plug latch is unmated from the jack latch with a disengagement force, normally by deflecting a mating latch. The disengagement force is greater than the engagement force so that the plug coaxial connector and the jack coaxial connector can be locked in a mating configuration.
Spring fingers and a groove in mating coaxial connectors are positioned relative to latching members or housing surrounding these coaxial connectors so that a first mating force peak attributable to mating of the two coaxial connectors occurs prior to a second mating force peak attributable to mating the two latching members. The first and second mating force peaks do not overlap as the first subassembly is mated to the second subassembly, so that the maximum mating force can be maintained within acceptable limits.